In an environment containing flammable vapors, the arc producing circuit breakers are enclosed within an explosion-proof enclosure. Explosion proof enclosures provide a measure of safety by creating a barrier between flaming gases and the personnel operating the circuit breakers.
The circuit breakers inside the enclosure are designed to be toggled or tripped from the outside by an actuation assembly without opening the enclosure cover (e.g., a lid). The actuation assembly typically includes a shaft that couples a handle located outside the enclosure cover to a toggle of the circuit breaker located under the cover.
As can be appreciated, flame-proof enclosures are very expensive compared to ordinary location enclosures. As such, it is important to increase the density of circuit breakers in the enclosure as much as possible to reduce cost.
Conventionally, relatively large size of the actuation assemblies required additional spacing between adjacent circuit breakers. That meant that the manufacturers are forced to use much larger enclosures. For example, in a 41″×15″ enclosure, only about 42 miniature circuit breakers (e.g., Model S201-C20 from ABB of Zürich, Switzerland) can be populated even though more than approximately 60 breakers can be populated if no actuation assembly was needed.
Therefore, there is a need to provide an improved actuation assembly that allows a higher density of circuit breakers to be installed in an enclosure.